African Bird Club, funding report 2016: Understanding the drivers of Martial Eagle declines in the Kruger National Park, South Africa

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1 Dr. Arjun Amar Senior Lecturer Percy FitzPatrick Institute of African Ornithology DST/NRF Centre of Excellence University of Cape Town Rondebosch 7701 South Africa Tel: +27 (0) Fax: +27 (0) Internet: African Bird Club, funding report 2016: Understanding the drivers of Martial Eagle declines in the Kruger National Park, South Africa Rowen van Eeden 1, D. Phil Whitfield 2, Andre Botha 3, Arjun Amar 1 1) Percy FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, South Africa 2) Natural Research Ltd., Aberdeenshire, Scotland 3) Endangered Wildlife Trust Birds of Prey Programme, Modderfontein, Johannesburg, South Africa Pic. 1 Adult Martial Eagle fitted with a solar GPS PTT tracking tag Our Mission is to be an outstanding teaching and research university, educating for life and addressing the challenges facing our society.

2 Motivation Martial Eagles (Polemaetus bellicosus) are considered the largest (3 5.6 kg) eagle species in Africa (Brown et al., 1982). They have an African wide distribution with the exception of forests and true deserts. Approximately 600 pairs are suggested to occupy a range across South Africa (Taylor, 2015). The species is long lived (Paijmans, 2016), reaches sexually maturity at 6 years old and has a low fecundity fledging on average once chick every second year (Steyn, 1982). Martial Eagles are a low-density species with large home ranges; inter-nest distances average ca. 12 km (Tarboton and Allan, 1984). These extreme k-selected life history traits and small population sizes predispose the species to occupy relatively stable environments with low unnatural mortalities. Comparison of reporting rates from the South African Bird Atlas Projects 1 ( ) and 2 ( ongoing) detected Martial Eagles were declining (Pic 2.) across South Africa by as much as 60 % over the last 20 years (Amar et al., 2015, Cloete, 2013, Underhill, 2012). These declines contributed to the species being up-listed to Vulnerable by the IUCN in 2014 (Birdlife International, 2015). Declines were also detected in protected areas, for example Martial Eagles declined by 56 % in Kruger National Park (KNP; Cloete, 2013). KNP is a 20,000 km 2 reserve and South Africa s flagship national park. It is often regarded as the stronghold for Martial Eagles, hosting an estimated 110 breeding pairs (Tarboton and Allan, 1984). Pic. 2 Martial Eagle range change map showing the differences between SABAP1 and SABAP2 reporting rates in quarter degree squares ( Beyond protected areas Martial Eagles are prone to a number of threats including persecution, habitat transformation, electrocutions and drowning in farm reservoirs (Anderson et al., 1999, Brown, 1991, Herholdt, 1998, Herholdt and Kemp, 1997, Van Rooyen and Ledger, 1999). Although the main threats to Martial Eagles have been recognised for some time, the declines within protected areas were particularly alarming.

3 We hypothesised that even the largest protected areas are unlikely to conserve wide-ranging, low density apex predators with large home ranges, as they likely face threats beyond park boundaries during movements beyond park boundaries, and through edge effects (Penteriani et al., 2005, Woodroffe, 2003, Woodroffe and Ginsberg, 1998). We also hypothesised that changes in ecosystems may cause changes in the species breeding performance, thus driving population declines. In 2013 we began investigating the ecology of, and threats to, Martial Eagles in KNP and the surrounding regions (Pic 3.) using GPS tracking data. We also monitored breeding performance over the course of three years to determine if this may have driven the observed declines. These findings will allow us to understand the causes forof declines and inform the species conservation measures. Pic. 3 Location of Kruger National Park in relation to neighbouring countries and Provincial boundaries where eagles were GPS tracked The Africa Bird Club contributed to this research through the award of a grant of 1,500 in June 2013 to help fund the fitmentting of GPS tags to juvenile Martial Eagles. Aims 1) Investigate home range sizes, ranging behaviour and quantitatively test the habitat preference of adult Martial Eagles. Improve ecological knowledge on adult Martial Eagles in order to inform conservation outcomes and provide a benchmark for monitoring. 2) Understand juvenile dispersal and immature ranging behaviour. Do threats beyond protected area boundaries increase unnatural mortalities and result in recruitment failure back into protected areas?

4 3) Study the breeding performance of the species to understand if productivity is limiting population growth. Hypothesise potential drivers that could impact on breeding performance. Summary of results Key data collected GPS tagged 8 adult Martial Eagles to understand habitat use and ranging behaviour (Table 1). GPS tagged 9 juvenile/immature Martial Eagle to understand dispersal, ranging behaviour and habitat use (Table 2). Table 1. Tracking data summary for adult Martial Eagles GPS tracked in KNP. The attributed causes of transmission cessation are shown where applicable; devices still transmitting at the time of this report are represented by NA. Individual Sex Dates tracked Days GPS locations Transmission cessation (cause) G32554 F 09/10/ /09/ NA G32553 F 26/08/ /09/ NA G32551 F 01/08/ /07/ Hunted/persecuted G32555 F 12/09/ /02/ Conspecific conflict G32519 F 16/03/ /09/ NA G32516 F 22/03/ /05/ Hunted G32552 M 23/08/ /02/ Conspecific conflict PTT72154 M 30/07/ /08/ Electrocution Total N = Table 2. Summary of the juvenile Martial Eagles tracked to understand dispersal behaviour, and post dispersal habitat use. Prefixes (GSM/PTT) of individual identity numbers represent the type of tracking device used (see methods). Where mortalities or tag failures were detected the cause is indicated in parentheses. Age classes indicate at what stage of the birds life GPS tags were fitted. Individual Sex Dates tracked Days Hourly GPS locations Age tagged Transmission cessation (cause) GSM M 09/12/ /09/ Fledgling No PTT F 18/08/ /02/ Fledgling Yes (Unknown) PTT F 24/02/ /09/ PFDP No GSM F 09/01/ /04/ PFDP Yes (Unknown) GSM M 07/02/ /09/ < 1 year No GSM M 16/03/ /09/ < 1 year No GSM M 15/03/ /03/ < 1 year Yes (Unknown) GSM M No data 0 < 1 year Yes (Unknown) GSM F 02/02/ /09/ < 3 year Yes (Injured) Total N = Colour ringed an additional 24 adult eagles to investigate adult turn over/survival rates.

5 Initially monitored 20 known nest sites stemming from a 2011 aerial survey to determine if breeding performance was limiting the population growth. 65 nest sites were known across KNP in 2016 following two additional aerial surveys performed in 2014 and Key findings 1) Adults held large (ca 108 km 2 ) home ranges with little overlap. Thus even the largest national parks have a limited carrying capacity for breeding adults due to these large home range sizes (e.g. KNP: max. 185 pairs). Home range analysis suggests eagles used areas within their home ranges ranges that were associated with high tree cover, areas close to rivers, areas with relatively lower elevation, gradual slopes, and preferred dense bushveld over moderate bushveld or grass land. The decline of tall tree species in KNP is thus concerning given their preference for this habitat, however bush encroachment may benefit eagles in areas that are dominated by grasses. Previously it was thought that adults held home ranges throughout their breeding lives (Steyn, 1982), however we discovered a substantial nomadic population of adult non-breeders. Four nomadic adults ranged widely (ca. 44, 000 km 2 ). They had high mortality rates associated with anthropogenic threats (n = 3/4) during their large ranging movements (Pic 4). These included an electrocution in Swaziland, and two birds that were lost to subsistence hunting activities in neighbouring Mozambique. Two natural mortalities were also recorded of resident birds. Ring re-sightings were low and time dependent, thus we need to collect resightings for longer time periods, and greater sample sizes are required to calculate accurate survival estimates. Some birds lost their rings making individual identification difficult. New more robust rings are to be used in the future. Pic. 4 Release of a GPS -tagged adult Martial Eagle from Kruger National Park featured on ITV Fierce (left), recovered in a hunting snare (right) 60 days and ca. 195 km in Mozambique from its release location 2) We detected that juveniles had a prolonged post nesting dependency phase (7 9 months), where they remain reliant on parental provisioning. This limits the breeding periodicity of adults as juveniles remain in

6 the natal territory well into the next breeding season. During their dependency, juveniles develop flight and hunting skills and made numerous exploration trips beyond the natal territory before returning to the nest (ca. 150 km from nest). Juveniles experienced higher mortality during this time (n = 2/9). Although settlement was not detected after 36 months of tracking, individuals remained in large ranges (5, 900 km 2 ) that sometimes incorporated their nesting sites. The extent of movements was similar to non-breeding adults. Encouragingly relatively low mortality rates were detected after dispersal onset (n = 1/9). This was contradictory to the high mortality in adults, and we therefore require further tracking of both adults and juveniles in order to establish whether these mortality ratios are by change and due to small sample sizes. 3) Our breeding performance monitoring detected the lowest productivity (0.23 young per pair per year) yet to be recorded in any study on the species. Population models suggest that the current productivity rate is sufficient to drive declines in the absence of any other impacts e.g. decreased survival rates. Nest site distribution models and descriptions on nest site selection highlights the importance of tall (ca. 12 m) trees for nesting. Currently tall tree numbers are declining in KNP due to the impacts of increasing elephant numbers and changing fire regimes, and this is concerning. These data were collected during a drought that may have impacted on the breeding performance of the species by limiting prey abundance, however this remains to be tested. Direction of future research 1) We will continue to GPS tag additional adults to determine if high mortality and the extent of nomadism within the adult population was due to low sample size. Continue individual ID ringing to increase sample size. 2) Similarly, we will continue to GPS tag and monitor juvenile movements and hopefully detect settlement areas. We will establish an ID ringing programme to monitor survival rates of juveniles that was not performed in the previous study period due to logistical constraints. 3) We will continue monitoring breeding performance. Assess likely drivers of low productivity e.g. rainfall, fire regimes, prey abundance. Collections of prey remains will assist us to establish diet and diet trends. Research outputs A PhD (Conservation Biology, UCT) by Rowen van Eeden is currently nearing completion. One paper is currently under review at PLOS ONE and another three are nearing completion for submission to ISI listed journals. The results and activities of the Martial Eagle Project - Kruger National Park were disseminated through the publication of four magazine/news paper articles, a press release which was featured in numerous

7 newspapers (e.g. Daily Mail in the UK), one radio interview, two natural history television inserts, six conferences, and five bird club presentations (Table 3). We also engage with a wide community of citizens through a Facebook page with more than 1700 likes ( A poster to illicit ring re-sightings featured prominently in all tourist rest camps in the KNP and featured funders details. Table 3. Martial Eagle project outputs Type of communication Scientific publications Reference van Eeden, R., D.P. Whitfield., A. Botha., A. Amar Ranging behaviour and habitat preferences of the Martial Eagle: implications for the conservation of a declining apex predator. Under review. PLOS ONE van Eeden, R., D.P. Whitfield., A. Botha., A. Amar Natal dispersal and habitat preferences of juvenile Martial Eagles. In prep van Eeden, R., D.P. Whitfield., A. Botha., A. Amar Predicted distribution of Martial Eagles in Kruger National Park and the surrounding Provinces In prep van Eeden, R., D.P. Whitfield., A. Botha., A. Amar Breeding performance and nest site selection of Martial Eagles in Kruger National Park In prep. Semi-popular articles African birdlife. July/August 2013 SANParks Times. June 2014 African birdlife. March/April 2015 Wild Magazine. Summer 2014/2015 (A. Amar) Wild Magazine. Summer 2015/2016 African birdlife. July/August 2016 Radio interviews Television Lotus FM SABC, South Africa. (A. Amar) 50/ SABC, South Africa Fierce ITV, UK Conferences Endangered Wildlife Trust Birds of Prey Programme Annual Meeting Phalaborwa, Kruger National Park, South Africa Zoological Society of Soutern Africa Tshipise, Limpopo, South Africa Savanna Science Network Meeting Skukuza, Kruger National Park, South Africa Endangered Wildlife Trust Birds of Prey Programme Annual Meeting Etosha, Namibia

8 Raptor Research Foundation Sacramento, California, USA. Birdlife South Africa Skukuza, Kruger National Park, South Africa (A. Amar) Out-reach presentations Phalaborwa Bird Club, South Africa (2014) Somerset West Bird Club, South Africa (2015) Tygerberg Bird Club, South Africa (2015) West Coast Bird Club, South Africa (2015) Cape Bird Club, South Africa (2015) References AMAR, A., CLOETE, D. & WHITTINGTON, M Using independent nest survey data to validate changes in reporting rates of Martial Eagles between the Southern African Bird Atlas Project 1 and 2. Ostrich, 1-5. ANDERSON, M. D., MARITZ, A. W. & OOSTHUYSEN, E Raptors drowning in farm reservoirs in South Africa. Ostrich, 70, BIRDLIFE INTERNATIONAL The IUCN Red List of Threatened Species. BROWN, C Declining Martial Polemaetus bellicosus and Tawny Aquila rapax Eagle populations and causes of mortality on farmlands in central Namibia. Biological Conservation, 56, BROWN, L. H., URBAN, E. K. & NEWMAN, K The Birds of Africa, London, Academic Press CLOETE, D Investigating the decline of the Martial Eagle (Polemaetus bellicosus) in South Africa. University of Cape Town. HERHOLDT, J Survival threats and conservation management of raptors in the Kgalagadi Transfrontier Park. Transactions of the Royal Society of South Africa, 53, HERHOLDT, J. & KEMP, A Breeding status and ecology of the Martial Eagle in the Kalahari Gemsbok National Park, South Africa. Ostrich, 68, PAIJMANS, D New new longevity record of the Martial Eagle. Available from: ]. PENTERIANI, V., OTALORA, F., SERGIO, F. & FERRER, M Environmental stochasticity in dispersal areas can explain the mysterious disappearance of breeding populations. Proceedings of the Royal Society of London B: Biological Sciences, 272, STEYN, P Birds of prey of southern Africa, Cape Town, David Phillip. TARBOTON, W. R. & ALLAN, D. G The status and conservation of birds of prey in the Transvaal, Pretoria, Transvaal Museum. TAYLOR, M. R Martial Eagle Polemaetus bellicosus. In: TAYLOR, M. R., PEACOCK, F. & WANLESS, R. M. (eds.) The Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland. Johannesburg, South Africa: Birdlife South Africa. UNDERHILL, L. G Martial Eagles spiral downwards [Online]. University of Cape Town: Animal Demography Unit, Southern African Bird Atlas Project 2 (SABAP2). Available: [Accessed 12/08/ ]. VAN ROOYEN, C. & LEDGER, J Birds and utility structures: Developments in southern Africa. Ferrer, M. & G.. FM Janns.(eds.) Birds and Power lines. Quercus: Madrid, Spain,

9 WOODROFFE, R Dispersal and conservation: a behavioural perspective on metapopulation persistence. In: FESTA-BIANCHET, M. & APOLLONIO, M. (eds.) Ethology and Conservation. Island Press. WOODROFFE, R. & GINSBERG, J. R Edge effects and the extinction of populations inside protected areas. Science, 280,